Apparatus for leveling or straightening metal sheets



Dec. 18, 1951 E. MAYER 2,578,820

APPARATUS FOR LEVELING 0R STRAIGHTENING METAL SHEETS Filed Dec. 25, 1947 Pi .2 Fa .3

INVENTOR. EUGE NE MAYER AGENT Patented Dec. 18, 195i APPARATUS FOR LEVELING OR STRAIGHT- ENING METAL SHEETS Eugene Mayer, Strasbourg, France Application December 23, 1947, Serial No. 793,319 In France March 12, 1940 Section 1, Public Law 690, August 8, 1946 Patent expires March 12,1960

4 Claims.

The straightening of metal sheets of high quality is carried out in practice either by roller levellers or by stretching machines. Neither type of apparatus is, however, free from defects. The levellers have a large output and enable sheets. to be flattened in packs of two, three, or more at a time. As the sheets are passed through the levellers in a' lengthwise direction, the latter can be placed in line with other continuously operated machines in which the sheet undergo treatment, such as shears, oiling machines, etc. Frequently, however, the straightening efiect obtained'is not entirely satisfactory and, at any rate, notsufficient when the sheets are to be perfectly fiat, as is required, for instance, for sheets which are to be used in the manufacture of oflice furniture. Besides, it is not possible by straightening-sheets on a roller leveller to free the sheets entirely from the'internal stresses which are set up during the preceding rolling and annealing stages.

Stretching machines, on the other hand, give very good results as far as the straightening in itself is concerned, but their output is small and. the feeding of the sheets into the machines and their discharge therefrom are rather complicated. Furthermore, the jaws of the stretching machines which hold the sheets at their ends are liable to leave marks thereon, so that it is necessary to shear off the sheet ends, with a consequent loss of material.

The object of the present invention is to provide a method and apparatus which are capable of levelling and stretching metal sheets in one single operation, and which have the advantages of the two above methods and machines without their limitations.

The apparatus according to the present invention, comprises two or more roller leveller units arranged in one line and so close to each other that a sheet will enter one unit'before it is released by another one, at least one of the units being capable of exerting a stretching force on the sheet through the intermediary of the leveller rollers so that a sheet is subjected simultaneously to a stretching and to a levelling operation whilst. it is engaged by and advanced through two leveller units at a time.

In the following examples, only the most simple of various forms in which the invention can be carried out will be described, viz., the one in which the apparatus consists of two leveller units only. It is, however. to be understood that the provision of more than two leveller units in one and the same apparatu comes within the scope of the present invention.

The stretching force on the sheet can be produced in two diflerent ways, either by giving to the rollers of the second leveller unit a higher surface speed than to those of the first one, or by increasing the distance between the'twoleveller units whilst the sheet is gripped by both units.

The difference in surface speed between the rollers of the second and the first unit 'can be achieved in a very simple manner by rotating the rollers of the second unit faster than those of the first unit, the speed of the second unit being ad justable if desired; or, alternatively, by fitting the second unit with rollers of larger diameter than the first one, or by any other suitable means.

In cases where ordinary commercial sheets are to be handled, the connection between the-two units may be rigid. For higher quality sheets, however, a non-rigid connection between the two units is to be preferred, inasmuch as the pull exerted by the second unit on thesheet tends to draw the two units together. A rigid connection between the two units would thencause the sheet to slide past the rollers, if the pull on the sheet is too strong. This would-result in the sheet being marked, which, whilst of no great consequence for ordinary commercial sheets, would constitute a serious defect in high quality sheets.

A non-rigid connection between the two units can be achieved by any means which will resist the approach of the two units towards each other. These means may be purely mechanical, embodying, for instance, springs, or they'may be hydraulic or pneumatic. The means should preferably further include a return mechanism which may be formed by springs, so that the second unit is brought back into its initial position as soon as a sheet has passed through the apparatus. The force which resists the approach of the two units towards each other may be made adjustable.

Reverting to the second of the two alternatives -for producing a stretching force on the sheet,

.' however, only to be regarded as illustrating exthe scope the the stretching force is effected by giving the rollers of the second unit a higher surface speed than those of the first unit.

Figs. 2 and 3 are details of a component of the apparatus according to Fig. 1 in two different positions.

Referring first to the apparatus shown in Fig. 1, a common frame l carries two leveller units II and I2 having separate housings which have top and bottom rollers l3 and H, and I and i6, respectively. The rollers l3 and I5 are staggered relative to the rollers l4 and I6 respectively as is usual in conventional roller levellers. All the rollers are power-driven through gears of conventional design which are, however, not shownhere for the sake of simplicity, the drive being such that the rollers l5 and I6 of the second unit turn at higher surface speeds than the rollers I3 and ll of the first unit. The unit I I is rigidly secured to the frame l0, whilst the unit I2 is adapted to move in guideways ll of the frame 10.

The housing [8 of the second unit l2 has a downward extension l9 which passes through a recess in the top of the frame [6. A spindle 2| is threaded into the extension l9 and carries at one end a piston 22 which slides in a cylinder 23. The cylinder is filled with a liquid of suitable viscosity. Arranged in the piston 22 are narrow ducts 24 which allow the liquid in cylinder 23 to pass slowly from one side of the piston 22 to the other. The wall of the cylinder 23 has a hole 25 which i of larger diameter than the ducts 24 and leads into a channel 26 provided in the wall of the cylinder parallel to its axis and permit liquid to flow from one side of the piston 22 to the other, so as to by-pass the piston. The flow of liquid through thi channel is controllable by a hand-operated valve 21. A returnspring 28 is inserted between the cover of the cylinder 23 and the extension l9.

The apparatus is operated as follows:

A sheet S is fed into the two leveller units II and I2 a shown in Fig. 1, and is simultaneously flattened by the rollers l3, I4 and I5, l6 and stretched between the two units, the stretching force being applied to the sheet in the plane of the sheet through the intermediary of the rollers themselves, since the rollers I5, l6 rotate at a higher surface speed than the rollers I3, I4. The reaction to the stretching of the sheet produces a force in the second unit I2 which tends to displace the Same in the direction of the arrow F.

This movement of the unit is, however, slowed down by the spring 28 and by the fluid displaced by the piston 22 in the cylinder 23. The rate of movement of the second unit I2 is dependent on the aperture at the outlet end of the by-pass channel 26 which apertureis controlled through the valve 21. The further the valve 21 enters the opening of the by-pass channel 26, the slower will be the movement of the unit l2.

When the valve 21 has closed the aperture completely, the liquid in the cylinder 23 can only flow through the narrow ducts 24, which offer considerable resistance to the flow of the liquid and thus produce the maximum braking force on the unit l2.

After the sheet has left the second unit l2, the spring 28 will return the same into its initial position. This spring has, therefore, a dual func- 4 tion; during the actual stretching operation it serves to increase the braking force on the movable leveller unit, whilst after the stretching operation it serves to return the movable leveller unit into its initial position.

In the above-described apparatus, the leveller unit l2 will return to its initial position at the same slow rate at which it moved forward during the stretching operation under the influence of the pull exerted by the sheet S. It is, however, desirable that the return movement of th s unit should occur at a faster rate, and this can be effected by means of the non-return valve shown in Figs. 2 and 3. This valve is attached to the piston 22, has a bore 29 of larger cross-section than the tw duct 24, and is adapted to be closed by a cone 30 when the piston 22 moves in the direction of the arrow G, Fig. 2, and opened when the piston 22 moves in the direction of the arrow H, Fig. 3. The resistance developed by the viscous fluid in the cylinder 23 during the return movement of the piston is, therefore, very small, and the return movement will take place at a comparatively high speed.

In the drawings, only one cylinder 23 is shown, but it is preferable to provide two cylinders instead, arranged symmetrically with respect to the plane of the sheet S, in order to avoid the formation of a couple of forces which would tend to tilt the sheet.

I claim:

1. An apparatus for straightening metal sheets comprising at least two sets of rollers arranged in tandem, each set consisting of two superimposed horizontal rows of rollers, the rollers of one row being staggered relative to those of the other row and the two sets being positioned near enough to each other to permit the sheet to be engaged by the rollers of one set prior to being released by the rollers of the other set, a housing supporting the first set of rollers, a housing supporting the second set of rollers, a frame, the first of said housings being secured to said frame and the second of said housings being slidable on said frame, power means for rotating rollers of both sets simultaneously but at different speeds,

whereby a stretching force is applied to the sheet in the plane of the sheet and the moveable housv in tandem, each set consisting of two superimposed horizontal rows of rollers, the rollers of one row being staggered relative to those of the other row and the two sets being positioned near enough to each other to enable a sheet to be engaged by the rollers of one set prior to being released by the rollers of the other set, a housing supporting the first set of rollers, a housing supporting the second set of rollers, a frame, the first of said housings being secured to said frame and the second of said housing being slidable on said frame, power means for rotating the rollers of both sets simultaneously but at different speeds whereby a stretching force is applied to the sheet in the plane of the sheet and the moveable housing is drawn towards the fixed housing whilst the sheet is engaged by and advanced through both sets of rollers at a time, elastic damping means opposing the approach of said moveable housing to said fixed housing and spring means 3 for returning said moveable housing into its initial position after the sheet has been released by the first set of rollers.

3. An apparatus for straightening metal sheets comprising at least two sets of rollers arranged in tandem, each set consisting of two superimposed horizontal rows of rollers, the rollers of one row being staggered relative to the rollers,

of the other row and the two sets being positionednear enough to each other to enable a sheet to be engaged by the rollers of one set prior to being released by the rollers of the other set, a housing supporting the first set of rollers, a housing supporting the second set of rollers, a frame, the first of said housings being secured to said frame and the second of said housings being slidable on said frame, power means for rotating the rollers of both sets simultaneously but at different speeds, whereby a stretching force is applied to the sheet in the plane of the sheet and the moveable housing is drawn towards the fixed housing whilst a sheet is engaged by and advanced through both sets of rollers at a time, a hydraulic damping cylinder, a piston displaceable in said cylinder and connected to said moveable housing, said piston having one or more passages to permit the flow of fluid from one side of the piston to the other, and a non-return valve constraining the flow of liquid through said passages only when said moveable housing is drawn towards said fixed housing.

4. An apparatus for flattening metal stock. comprising at least two sets of, straightening rollers through which the stock is passed in succession, said sets being disposed so close to each other that the stock i engaged by the rolls of the second set prior to its release from the first set, one of said sets being capable of a movement towards and away from the other set; means for rotating the rolls of the second set at a higher surface speed than the rolls of the first. set, whereby the movable set is drawn towards the other set while the stock is engaged by both sides; and means for applying a force to the movable set opposing the approach of the movable set to the other set, whereby the sheet is subjected to a stretching action.

EUGENE MAYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 437,413 Eckerson Sept. 30, 1890 1,467,880 Roemer Sept. 11, 1923 2,004,596 Biggert, Jr June 11, 1935 2,432,828 Stone Dec. 16, 1947 2,140,533 MacChesney Dec. 20, 1938 

